STUTTGART, Germany - After more than three months out of the game due to a low back injury, German No.1 Andrea Petkovic made a winning return to the WTA during Tuesday's night session at the Porsche Tennis Grand Prix.

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Petkovic went into the Australian season as the No.10 player in the world, but a stress fracture in her back caused her withdrawal from the Australian Open and subsequent pull-outs from Paris, Doha, Dubai, Indian Wells and Miami. The absence didn't hurt her ranking too much - she is now No.12 - but could coming back at such a stacked Premier-level tournament be too much?

"It has always been my goal to compete at the top level," Petkovic said. "I always told myself, if you're not good enough to compete with the best, don't play tennis at all. So when I was planning on coming back I was conscious of coming back here, where all the Top 8 are playing, and I'm not seeded so I could play any of them in the first round. I believe to throw somebody into the cold water is better than dipping and seeing how cold it might get."

Having played two matches in Fed Cup over the weekend - losing in singles but winning in doubles - Petkovic made a winning return to WTA-level competition in Stuttgart, beating fellow German Kristina Barrois first round, 61 64.

"I'm actually surprised it went so well today," Petkovic said. "It was a tough challenge playing Stosur in Fed Cup on the weekend, playing the No.5 player in the world right after three and a half months off. I was in my rhythm tonight and played quite solid. I was very stable emotionally and mentally out there."

The level will step up in a big way for Petkovic in the next match, as she faces top-ranked, top-seeded Victoria Azarenka in the second round. Azarenka beat Petkovic in their only previous meeting, which was back in 2010.

"I didn't watch a lot of tennis while I was out but I saw her winning streak and rise to No.1," Petkovic said. "I really think she's the best right now. She deserves to be No.1, and as a character and personality she's a proper No.1.

"It's a tough challenge, but as I said, this is why I play tennis."

All three seeded players in action won in straight sets, namely No.5 seed Sam Stosur, No.7 seed Marion Bartoli and, in the last match of the day No.8 seed Li Na, who blasted eight aces to beat the tricky Lucie Safarova, 76(4) 64.

Other winners were Francesca Schiavone, Angelique Kerber, Julia Goerges and qualifiers Greta Arn and Alizé Cornet. Kerber scored a 62 63 win over Roberta Vinci, running her indoor winning streak to 12 matches.

Top seeds Kveta Peschke and Katarina Srebotnik and Argentine duo Gisela Dulko and Paola Suárez were among the winners in first round doubles play.